Fission barrier of superheavy nuclei and persistence of shell effects at high spin: cases of 254No and 220Th

Greg Henning; T L Khoo; A Lopez-Martens; D Seweryniak; M Alcorta; M Asai; B B Back; P F Bertone; D Boilley; M P Carpenter; C J Chiara; P Chowdhury; B Gall; P T Greenlees; G Gürdal; K Hauschild; A Heinz; C R Hoffman; R V F Janssens; A V Karpov; B P Kay; F G Kondev; S Lakshmi; T Lauritsen; C J Lister; E A McCutchan; C Nair; J Piot; D Potterveld; P Reiter; A M Rogers; N Rowley; S Zhu

doi:10.1103/PhysRevLett.113.262505

Fission barrier of superheavy nuclei and persistence of shell effects at high spin: cases of 254No and 220Th

Phys Rev Lett. 2014 Dec 31;113(26):262505. doi: 10.1103/PhysRevLett.113.262505. Epub 2014 Dec 30.

Authors

Greg Henning¹, T L Khoo², A Lopez-Martens³, D Seweryniak², M Alcorta², M Asai⁴, B B Back², P F Bertone², D Boilley⁵, M P Carpenter², C J Chiara⁶, P Chowdhury⁷, B Gall⁸, P T Greenlees⁹, G Gürdal¹⁰, K Hauschild³, A Heinz¹¹, C R Hoffman², R V F Janssens², A V Karpov¹², B P Kay², F G Kondev², S Lakshmi⁷, T Lauritsen², C J Lister⁷, E A McCutchan², C Nair², J Piot⁸, D Potterveld², P Reiter¹³, A M Rogers², N Rowley¹⁴, S Zhu²

Affiliations

¹ CSNSM, IN2P3-CNRS, and Université Paris Sud, Bat. 104-108, F-91405 Orsay, France and Argonne National Laboratory, Argonne, Illinois 60439, USA.
² Argonne National Laboratory, Argonne, Illinois 60439, USA.
³ CSNSM, IN2P3-CNRS, and Université Paris Sud, Bat. 104-108, F-91405 Orsay, France.
⁴ Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195, Japan.
⁵ GANIL, CEA-DSM, and IN2P3-CNRS, B.P. 55027, F-14076 Caen Cedex, France and Université de Caen Basse-Normandie, F-14032 Caen Cedex, France.
⁶ Argonne National Laboratory, Argonne, Illinois 60439, USA and University of Maryland, College Park, Maryland 20742, USA.
⁷ University of Massachusetts Lowell, Lowell, Massachusetts 01854, USA.
⁸ Université de Strasbourg, IPHC, 23 rue du Loess, 67037 Strasbourg, France and CNRS, UMR7178, 67037 Strasbourg, France.
⁹ Department of Physics, University of Jyväskylä, FI-40014 Jyväskylä, Finland.
¹⁰ Argonne National Laboratory, Argonne, Illinois 60439, USA and DePaul University, Chicago, Illinois 60604, USA.
¹¹ Fundamental Fysik, Chalmers Tekniska Hogskola, 412 96 Göteborg, Sweden and WNSL, Yale University, New Haven, Connecticut 06511, USA.
¹² Flerov Laboratory of Nuclear Reactions, JINR, Dubna, 141980, Russia.
¹³ Institut für Kernphysik, Universität zu Köln, D-50937 Köln, Germany.
¹⁴ IPN, CNRS/IN2P3, Université Paris-Sud 11, F-91406 Orsay Cedex, France.

PMID: 25615317
DOI: 10.1103/PhysRevLett.113.262505

Abstract

We report on the first measurement of the fission barrier height in a heavy shell-stabilized nucleus. The fission barrier height of 254No is measured to be Bf=6.0±0.5 MeV at spin 15ℏ and, by extrapolation, Bf=6.6±0.9 MeV at spin 0ℏ. This information is deduced from the measured distribution of entry points in the excitation energy versus spin plane. The same measurement is performed for 220Th and only a lower limit of the fission barrier height can be determined: Bf(I)>8 MeV. Comparisons with theoretical fission barriers test theories that predict properties of superheavy elements.